Food allergy is an immunologically mediated clinical syndrome that develops after the ingestion of a dietary product. The adverse reaction that accompanies a food allergy is often an immediate immunoglobulin E (IgE) mediated reaction, otherwise known as food protein allergy. Host, A., et al., Dietary Products Used in Infants for Treatment and Prevention of Food Allergy, Arch. Dis. Child 81:80-84 (1999). Symptoms of food protein allergy include angioedema, urticaria, eczema, asthma, rhinitis, conjunctivitis, vomiting, or anaphylaxis.
Cow's milk allergy is the most common food protein allergy in young children and occurs in about 2% to 3% of all infants. Sampson, H. A., Food Allergy. Part 1: Immunopathogenesis and Clinical Disorders, J Allergy Clin Immunol. 103:717-728 (1999). One possible explanation for the prevalence of cow's milk allergy among infants is that intact cow's milk protein, which is found in most conventional infant formulas, is the earliest and most common food allergen that infants are exposed to. In addition, infants may be especially susceptible to cow's milk allergy because their intestinal mucosa have a greater permeability to incompletely digested macromolecules than do adults. Moran R., Effects of Prolonged Exposure to Partially Hydrolyzed Milk Protein, J. Pediatr. 121:S90-S4 (1992).
While there is no known treatment that can completely cure cow's milk allergy, it may be possible to prevent or lessen cow's milk and other allergies in infants through the consumption of hydrolyzed protein formulas. It has been shown that the consumption of infant formulas having partially and extensively hydrolyzed proteins in place of conventional formulas having only intact proteins may reduce the risk of future allergies in infants. Id. Thus, if an infant has a family history of allergies, consumption of hydrolyzed protein formulas may reduce the risk of that child developing an allergy in the future.
Hydrolyzed protein formulas can be characterized as extensively hydrolyzed or partially hydrolyzed. Extensively hydrolyzed protein-containing infant formulas (EHF) are based on cow's milk, but the proteins have been treated with enzymes to break down most of the proteins that cause allergy-related symptoms. One example of a commercially-available EHF is Enfamil® Nutramigen®. It is a casein-based hypoallergenic infant formula for term infants who are sensitive to intact proteins in cow's milk and soy formulas. Partially hydrolyzed protein-containing infant formulas (PHF), on the other hand, have been treated with enzymes to break down only some of the milk proteins.
Ideally, any infant formula, including PHF, should simulate human milk as closely as possible. In human milk, there are two main proteins, whey protein and casein. Whey protein typically composes about 60% of the protein in human milk, while casein typically composese about 40%. Lonnerdal, B., Biochemistry and Physiological Functions of Human Milk Proteins, Am. J. Clin. Nutr. 42:1299-1317 (1985).
In addition to simulating the protein content of human milk, a PHF should not cause or exacerbate difficulties in carbohydrate absorption. The major carbohydrate in cow's milk-based infant formula is lactose. Lactose is a disaccharide of glucose and galactose and the enzyme lactase is required for the body to digest lactose. If lactase, which is located on the surface membrane of intestinal epithelial cells, is not present in sufficient amounts, the body may be unable to completely digest lactose. This condition, which is commonly known as lactose intolerance, can lead to symptoms such as abdominal bloating, gas, cramps and diarrhea.
One way to avoid the unwanted side effects of lactose intolerance in infants is to provide a low-lactose infant formula for nutritional supplementation or human milk replacement. A low-lactose infant formula typically has a small percentage of carbohydrates comprising lactose. The remaining carbohydrate content is derived from another source, such as corn syrup solids.
Various infant formulas have been disclosed, but none provide the combined benefits of the present invention. For example, U.S. Pat. No. 5,405,637 to Martinez, et al. relates to a milk protein partial hydrolysate and infant formula containing the same. The patent does not, however, disclose an infant formula having a lactose content between about 0% and 60%. Additionally, although the reference discloses a degree of hydrolysis between about 6 and 9%, the protein hydrolysate of the Martinez reference does not disclose having the molecular weight of the protein hydrolysate employed in the present invention.
U.S. Pat. No. 6,777,931 to Kratky relates to an infant formula composition having a low threonine content. While the reference discusses the use of whey protein and casein, the whey protein used is modified so that the caseino-glyo-macropeptide (cGMP) has been removed. Additionally, the reference does not disclose an infant formula having a partial hydrolysate with the particular molecular weight profile as in the present invention.
U.S. Pat. No. 6,162,472 to Griffin, et al. relates to an infant formula comprised of casein and whey protein and having a lactose content of less than 20%, but does not disclose a partial hydrolysate formula.
U.S. Pat. No. 6,171,621 to Braun, et al., U.S. Pat. No. 6,863,918 to Bindels, et al., and U.S. Pat. No. 6,194,009 to Kamarel all relate to various infant formulas and nutritional products based on protein hydrolysates. The patents do not, however, disclose a supplement or formula having a whey protein:casein ratio between about 50:50 and 70:30. Additionally, the partial hydrolysates of the various patents do not disclose hydrolysates with the molecular weight employed in the present application.